从 NSuserDefaults 取消归档数据的正确方法是什么？
我将一些基于 Objective C 的对象存储到 NSuserdefaults 中。
为了从 NSuserDefaults 检索数据，我使用 initWithCoder 方法。
我见过两种不同的实现：
实现 1
- (id)initWithCoder:(NSCoder *)decoder {
self = [super init];
if (self != nil){
//decode properties, other class vars
self.variable = [decoder decodeObjectForKey:@"variable"];
}
return self;
}
实现 2
- (id)initWithCoder:(NSCoder *)decoder {
self = [[CustomClass alloc] init];
if (self != nil){
//decode properties, other class vars
self.variable = [decoder decodeObjectForKey:@"variable"];
}
return self;
}
哪个是正确的方法？
这两者有什么区别？
I am storing some Objective C based objects in to NSuserdefaults.
To retrieve data from NSuserDefaults, I use initWithCoder method.
I have seen two different implementations of this:
Implementation 1
- (id)initWithCoder:(NSCoder *)decoder {
self = [super init];
if (self != nil){
//decode properties, other class vars
self.variable = [decoder decodeObjectForKey:@"variable"];
}
return self;
}
Implementation 2
- (id)initWithCoder:(NSCoder *)decoder {
self = [[CustomClass alloc] init];
if (self != nil){
//decode properties, other class vars
self.variable = [decoder decodeObjectForKey:@"variable"];
}
return self;
}
Which is the correct way?
What is the difference between these two?
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评论（2）
你不应该在方法中分配你的对象（分配发生在调用 init/initWithCoder 之前）。你的代码应该是这样的：
you shouldn't be alloc'ing your object in an method (the alloc takes place before init/initWithCoder is called). your code should look like:
这实际上不是 NSUserDefaults 实现的区别，而是您的类是否是子类的区别。子类调用 [super init] 来获取其超类的属性（例如 2），否则您可以只分配并初始化自定义类（例如 1）。
This really isn't a difference in NSUserDefaults implementation, the difference whether or not your class is a subclass. Subclasses call [super init] to gain the properties of their superclasses (ex. 2), otherwise you can just alloc and init the custom class (ex. 1).